1. Field of the Invention
This invention relates to a fallboard arrangement for a keyboard instrument, such as an electronic piano, for opening and closing a performance section, including a keyboard, of the keyboard instrument, by sliding a fallboard thereof in a front-rear direction.
2. Description of the Prior Art
FIG. 10 shows a conventional fallboard arrangement of the above-mentioned kind. The fallboard arrangement 50 is applied to an electronic piano 60 and includes a fallboard 51. The fallboard 51 is mounted to a piano body 61 such that it can slide in a front-rear direction between a closed position (indicated by solid lines in FIG. 10) for closing a performance section of the electronic piano 60 and an open position (indicated by two-dot chain lines in the figure) for opening the same.
As shown in FIGS. 11A, 11B, the fallboard 51 includes a fallboard main section 52 in the form of a rectangular plate which is long sideways i.e. in a left-right direction, as well as a fallboard front section 53 and a fallboard rear section 54 which are also long sideways. The fallboard front and rear sections 53, 54 are fastened to the respective front and rear ends of the fallboard main section 52 by screws. The fallboard front section 53 has left and right front projections 53a, 53a outwardly projecting leftward and rightward from respective lower left and right corners thereof.
On the other hand, as shown in FIGS. 12A, 12B, the fallboard rear section 54 has a lower end to which a rotary shaft 55 is rotatably mounted. The rotary shaft 55 has left and right end portions fitted with respective left and right gear members 56. Each of the gear members 56 is a unitary member comprised of a rear projection 56a, a pinion 56b, and so forth, which are arranged in line in the mentioned order from the outside and integrally formed with each other. The gear member 56 is fixed to the rotary shaft 55 by a screw 57 screwed into the rotary shaft 55 through a slot 56c formed through the gear member 56.
The piano body 61 has left and right arms 61a, 61a to which left and right front guide rails 62, 62 and left and right rear guide rails 63, 63 are attached, respectively. Each front guide rail 62 extends forward and downward along a corresponding one of the arms 61a. The front guide rail 62 is formed with a front guide groove 62a extending over the whole length thereof. The front projection 53a is slidably engaged with the front guide groove 62a. 
On the other hand, each of the rear guide rails 63 extends along a corresponding one of the arms 61a in the front-rear direction. The rear guide rail 63 includes a rear guide groove 63a and a rack 63b integrally formed with each other. The rear guide groove 63a and the rack 63b each extend over the whole length of the rear guide rail 63 in a manner forming a slightly upwardly curved arcuate shape, not shown. The rear projection 56a is slidably engaged with the rear guide groove 63a, and the pinion 56b is meshed with the rack 63b. Further, in plan view, the left and right ends of the fallboard 51 overlap the respective racks 63b, 63b (see FIG. 10).
Thus, when the fallboard 51 is drawn forward or pushed rearward, the front projections 53a are guided by the respective front guide rails 62, and the rear projections 56a by the respective rear guide rails 63, while the pinions 56b in mesh with the respective racks 63b rotate, whereby the fallboard 51 is moved in the front-rear direction without turning sideways with respect to the piano body 61.
During assembly of the electronic piano 60, the length of the rotary shaft 55 in the direction of width of space between the arms 61a, 61a is adjusted according to an actual distance between the arms 61a, 61a so as to place the gear members 56, 56 in engagement with the respective left and right rear guide grooves 63a, 63a in a proper positional relationship. More specifically, a proper position of each gear member 56 for engagement with the corresponding rear guide groove 63a is located by shifting the gear member 56 with respect to the rotary shaft 55 in the left-right direction. Then, when the proper position is located, the gear member 56 is fixed to the rotary shaft 55 by the screw 57. On the other hand, when the fallboard 51 is required to be dismounted from the piano body 61 e.g. for maintenance of the electronic piano 60, the screws 57 are turned and loosened, and then the gear members 56 are each shifted inward by relatively sliding the screw 57 along the slot 56c. As a result, the rotary shaft 55 including the left and right gear members 56 is shortened and thereby dismounted from the rear guide rails 63. Then, the front projections 53a, 53a are each disengaged from the corresponding front guide rail 62 via an opening of the rear end of the front guide rail 62. Thus, the fallboard 51 is dismounted from the piano body 61. Thereafter, when the fallboard 51 is mounted to the piano body 61 again, the mounting operation is carried out by the reverse of the above procedure, and at the same time, the rotary shaft 55 is adjusted in length.
In the above conventional fallboard arrangement 50, however, in order to mount the fallboard 51 to the piano body 61 during assembly of the electronic piano 60 or to dismount the fallboard 51 from the piano body 61 e.g. for maintenance of the electronic piano 60, as well as in order to adjust the length of the rotary shaft 55 in the direction of width of the space, it is required to lengthen or shorten the rotary shaft 55 by turning and loosening the screws 57, 57 provided at the respective left and right end portions of the rotary shaft 55 and then axially moving the gear members 56, 56 also fitted on the respective left and right end portions of the rotary shaft 55, which is troublesome and laborious. Further, since the racks 63b, 63b each form an upwardly curved arcuate shape and the left and right ends of the fallboard 51 overlap the respective left and right racks 63b, 63b in plan view, if the thickness of the fallboard main section 52 is increased e.g. due to design change of the fallboard 51, the bottom surfaces of the portions of the fallboard 51 overlapping the respective racks 63b are caught in the racks 63b during sliding of the fallboard 51. Even when the thickness of the fallboard main section 52 is not increased, if the racks 63b are designed to extend rearward and downward particularly with a view to preventing the fallboard 51 from being closed by its own weight during its opening or closing operation, the bottom surfaces of the portions of the fallboard 51 overlapping the respective racks 63b can be caught in the racks 63b similarly to the above case. In the conventional fallboard arrangement 50, as is apparent e.g. from the above fact that it is impossible to increase the thickness of the fallboard main section 52, the degree of freedom in designing the fallboard 51 is low.
It is an object of the invention to provide a fallboard arrangement for a keyboard instrument, which has a construction facilitating operations of mounting and dismounting a fallboard as well as an operation of adjusting the length of a rotary shaft of the fallboard, and makes it possible to enhance the degree of freedom in designing the fallboard.
To attain the above object, the present invention provides a fallboard arrangement for a keyboard instrument, for opening and closing a performance section including a keyboard and arranged within a body of the keyboard instrument, by being slid in a front-rear direction.
The fallboard arrangement according to the invention is characterized by comprising:
a fallboard mounted to the body of the keyboard instrument, for opening and closing the performance section;
a rotary shaft extending in a left-right direction and rotatably mounted to the fallboard such that the rotary shaft can be axially lengthened and shortened;
a pair of left and right pinions arranged at respective left and right ends of the rotary shaft such that the pair of left and right pinions and the rotary shaft form a one-piece assembly;
a pair of racks arranged in the body of the keyboard instrument and extending in the front-rear direction at respective locations outward of left and right ends of the fallboard, the pinions being meshed with the pair of racks, respectively; and
a pair of guides arranged in the body of the keyboard instrument such that the pair of guides extend along the pair of racks in the front-rear direction at respective locations outward of the left and right ends of the fallboard, the pair of guides having a pair of guide grooves for being engaged with the left and right ends of the rotary shaft, respectively, and thereby guiding the fallboard to slide in the front-rear direction.
According to this fallboard arrangement for a keyboard instrument, the performance section is opened and closed by sliding the fallboard in the front-rear direction. When the fallboard is slid, the left and right ends of the rotary shaft are guided by the guide grooves of the pair of guides, and the pair of pinions in mesh with the pair of racks are rotated. As a result, the left and right ends of the rotary shaft travel an identical distance, so that even when the fallboard is opened or closed by being drawn or pushed by a force biased toward one side, the fallboard is smoothly slid in the front-rear direction without turning sideways with respect to the piano body, which enables smooth opening and closing of the fallboard. Further, since the rotary shaft can be shortened or lengthened, it is possible to disengage the pinions from the racks, and the left and right ends of the rotary shaft from the guide grooves, by shortening the rotary shaft. This makes it possible to mount or dismount the fallboard to or from the piano body or adjust the length of the rotary shaft. Moreover, at respective locations outward of the left and right ends of the fallboard, the pinions are meshed with the racks, and the left and right ends of the rotary shaft are engaged with the pair of guide grooves, so that differently from the conventional fallboard arrangement, the left and right ends of the fallboard do not overlap the racks and guides in plan view. This construction prevents the fallboard from interfering with the racks or the guides even when the thickness of the fallboard is changed or when the racks are formed in a manner extending rearward and downward, and hence it is possible to enhance the degree of freedom in designing the fallboard. It should be noted that in the present specification, a member, including a pin wheel, which is meshed with the rack and rotated is referred to as xe2x80x9cthe pinionxe2x80x9d.
Preferably, the rotary shaft includes two shaft members disposed along an axis of the rotary shaft and movable along the axis relative to each other, and a fixing element arranged in a central portion of the rotary shaft, for fixing the two shaft members at respective positions to which the shaft members are moved relative to each other.
According to this preferred embodiment, it is possible to lengthen or shorten the rotary shaft by releasing the two shaft members fixed to each other by the fixing element, from the fixed state, through operations effected on the central portion of the rotary shaft, and axially moving the shaft members relative to each other. Further, by fixing the shaft members with respect to each other at the positions to which the shaft members have been relatively moved, it is possible to adjust the length of the rotary shaft. Thus, the operations for mounting and dismounting the fallboard as well as the operation for adjusting the length of the rotary shaft can be carried out on the central portion of the rotary shaft, and hence these operations are easy to carry out, differently from the prior art.
Preferably, the two shaft members are each formed by a hollow member having open opposite ends, and the fixing element comprises a connecting rod for being inserted into an inner one of the open opposite ends of each the follow member, a slot formed in each the hollow member, and screws for each being screwed through the slot into the connecting rod.
More preferably, the left and right ends of the rotary shaft and the pair of left and right pinions are integrally formed, together with a pair of rollers, and a pair of insertion portions, to form a pair of gear members, respectively, and the body of the keyboard instrument is formed with a pair of rolling contact surfaces at respective location inward of the pair of racks, for allowing the pair of rollers to be in rolling contact therewith, the pair of insertion portions being each inserted into the inner one of the open opposite ends of the hollow member corresponding thereto.
Further preferably, the fallboard arrangement includes a pair of guide rails attached to the body of the keyboard instrument, and the pair of racks, the pair of guides, and the pair of rolling contact surfaces are integrally formed on the pair of guide rails, respectively.
Further preferably, the two shaft members and the connecting rod are made of metal, and the pair of gear members are made of a synthetic resin.
Still more preferably, the pair of gear members each have a core rod made of metal and coaxially embedded therein.
Preferably, the body of the keyboard instrument includes a pair of arms each extending in the front-rear direction and having an inner surface, and the pair of racks and the pair of guides are each arranged in the inner surface of a corresponding one of the pair of arms.
Preferably, the fallboard has a rear end, and a front end having left and right end portions, the rotary shaft being mounted to the fallboard along the rear end thereof, the body of the keyboard instrument being formed with a second pair of guide grooves corresponding to the pair of guide grooves, respectively, the fallboard having a pair of pins provided thereon such that the pair of pins extend outwardly in a left-right direction from the left and right end portions of the front end of the fallboard, respectively, for being engaged with the second pair of guide grooves.
More preferably, the fallboard includes a fallboard main section, and a fallboard front section, the fallboard front section having a lower end having left and right end portions, and the pair of pins are arranged at the left and right end portions of the lower end of the fallboard front section.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.